Romney rallied his supporters Tuesday night at Red Rocks amphitheater, where an overflow crowd crammed into the 9,500-seat venue.

Obama called out the troops Wednesday afternoon in a chilly Denver City Park, and 16,000 people attended, said the city fire chief.

For both campaigns, the rallies were a show of strength in a crucial swing state where voting is already under way.

Gov. John Hickenlooper helped introduce Obama.

“I love Red Rocks more than just about anybody, but it could never hold all of you guys,” he told the crowd.

Obama made Wednesday’s stop as part of a two-day, eight-state tour that will include a stop in Chicago so he can vote.

“We are pulling an all-nighter. No sleep,” Obama said.

Romney and running mate Paul Ryan have criticized Obama for running a negative campaign and saying little about his vision for a second term. In response, Obama released a 20-page booklet laying out his plans.

“I want you to compare my plan to Governor Romney’s,” Obama said at Wednesday’s rally. “See what plan is best for you. See what plan is best for America’s future.”

But the president didn’t abandon his attack on Romney’s record and repeated his “Romnesia” joke about what he calls the Republican’s shifting positions, especially on social issues such as abortion.

“In the final weeks of the election, he’s counting on you forgetting what he stands for,” Obama said. “Trust matters. I think one thing you’ve seen, Colorado, over the last four years, is I mean what I say.”

He pointed to promises he made and said he kept: ending the war in Iraq, winding down the war in Afghanistan, cutting middle-class taxes and repealing the military’s “don’t ask, don’t tell” policy for gay and lesbian troops.

“If you want a real recovery, we’re going to have to have a real change. The president said he was a president of change. But in fact he’s become a president of status quo. And the policies of the president are a continuation of what we have seen over the last four years,” Romney said Tuesday night.

With less than two weeks to go, the election is coming down to about eight swing states. Most prognosticators agree that unless either candidate wins Ohio, he will have a hard time winning the race.

But if Obama takes Ohio, he’ll need at least one other swing state like Colorado. Romney is counting on a win in Colorado regardless of the outcome in Ohio.